In an automotive vehicle, it is desired, in the event of a collision, to deploy the air bag to protect an adult occupant in the seat. However, it is not desired to deploy the air bag when the seat is empty. Also, it may be desirable not to deploy the air bag when the seat is occupied by a child in a car seat. For the purpose of determining whether the seat is occupied by an adult, by a car seat, or some other object, a sensor is commonly included in the seat to detect the weight of the occupant. A common sensor device uses a bladder containing a fluid and a pressure sensor for determining the pressure of the fluid, where the pressure of the fluid is proportional to the weight of the occupant. Fluid needs to be injected into the bladder, and the bladder needs to be sealed, adding cost to the assembly. The inclusion of the pressure sensor also adds cost to the assembly. There is additional cost in incorporating the entire assembly into the seat. Servicing the common sensor device often requires removal of the vehicle seat along with replacement of the seat cushion to access and replace the bladder and pressure sensor assembly.
Therefore, what is needed is an improved seat assembly for sensing a weight of an occupant that is made of low cost components, is readily incorporated into the seat while maintaining the comfort of the occupant, is reliable to provide an output proportional to the weight, and is conveniently located for serviceability.